PROCESS FOR PREPARING (R OR S)-5-{1-AZIDO-3-[6-METHOXY-5-(3-METHOXY-PROPOXY)-PYRIDIN-3-YLMETHYL]-4-METHYL-PENTYL}-3-ALKYL-DIHYDRO-FURAN-2-ONE

摘要

Compounds of the formula (E), in which R'3 is isopropyl and R'4 is C1-C8-alkyl, and in which the carbon atom to which the R'3 radical is bonded has either (R) or (S) configuration, preference being given to (R) configuration, are obtainable in high yields A) by a stereoselective addition of isopropyl-substitutedpropionic esters to 6- methoxy-5-(3-methoxypropoxy)pyridine-3-carbaldehyde to give corresponding 2- {hydroxy-[6-methoxy-5-(3-methoxypropoxy)pyridin-3-yl]methyl}-3-methylbutanoic esters, subsequent conversion of the OH group to a leaving group, and a subsequent regioselective elimination to give 2-[1-[6-methoxy-5-(3-methoxypropoxy)pyridin-3-yl]- meth-(E)-ylidene]-3-methylbutanoic esters, followed by 1) hydrolysis to give the corresponding 2-[1-[6-methoxy-5-(3-methoxypropoxy)- pyridin-3-yl]meth-(E)-ylidene]-3-methylbutanoic acid, the enantioselective hydrogenation thereof to the corresponding chiral 2-[6-methoxy-5-(3-methoxy- propoxy)pyridin-3-ylmethyl]-3-methylbutanoic acid and the reduction thereof,or 2) hydrolysis to the corresponding 2-[1-[6-methoxy-5-(3-methoxypropoxy)pyridin-3- yl]meth-(E)-ylidene]-3-methylbutanoic acid, the reduction thereof to the corresponding 2-[1-[6-methoxy-5-(3-methoxypropoxy)pyridin-3-yl]meth-(E)-ylidene]-3- methylbutan-1-ol and the enantioselective hydrogenation thereof, or 3) reduction to the corresponding 2-[1-[6-methoxy-5-(3-methoxypropoxy)pyridin-3-yl]- meth-(E)-ylidene]-3-methylbutan-1-ol and the enantioselective hydrogenation thereof, or B) by a Sonogashira coupling of 5-bromo-2-methoxy-3-(3-methoxypropoxy)pyridine, SP-P2216_ATE -80- 5-iodo-2-methoxy-3-(3-methoxypropoxy)pyridine or of trifluoromethanesulphonic acid 6-methoxy-5-(3-methoxypropoxy)pyridin-3-yl ester with 2-propyn-1-ol to give 3-[6- methoxy-5-(3-methoxypropoxy)pyridin-3-yl]prop-2-yn-1-ol, followed by addition of an R' 3-Grignard compound to give 2-[1-[6-methoxy-5-(3-methoxypropoxy)pyridin-3-yl]- meth-(E)-ylidene]-3-methylbutan-1-ol and the enantioselective hydrogenation thereof; substitution of the chiral 2-[6-methoxy-5-(3-methoxy-propoxy)-pyridin-3-ylmethyl]-3- methyl-butan-1-ol resulting from pathways A) or B)to give 5-(2-halomethyl-3-methyl- butyl)-2-methoxy-3-(3-methoxy-propoxy)-pyridine, coupling thereof with a (E)-(R)-5- halo-2-alkyl-pent-4-enoic acid amide, followed by halogenation,hydroxylation lactonizatization and azidation.